In many ways in contemporary society, we are less civil and more forward than we have been in a long time. Or, at least, we are so in many more contexts. There are so many things said to me by students, for example, that utterly surprise me for no other reason than I cannot have imagined myself having said anything similar when I was in college.
But, we seem to have adopted a new strategy, both in person and in the virtual realm: the strategy of saying "just kidding" or "I was only joking".
This seems to get used in two different but related contexts. In one case, a person will say something utterly insulting or indefensible or factually insupportable or sexist or racist or clearly uncalled for and then follow it with "just kidding". In the other, a person makes a statement and then, afraid that they might be wrong, following it with the same.
Though the situations are very different, it seems in both cases there is both a statement of one's real character or knowledge or ignorance and then a wish that it wasn't so. If you know who are and aren't happy about it or ashamed about it, it seems that you have two choices: fix yourself or own up to it. This attempt to have it both ways, I think, shows the basest lack of character.